Ultrafast time-resolved transient absorption spectroscopy is able to monitor the fate of the excited state population in molecular aggregates or polymers. Due to many competing decay processes, the identification of exciton-exciton annihilation (EEA) is difficult. Here, we use a microscopic model to describe exciton annihilation processes in squaraine-squaraine copolymers. Transient absorption time traces measured at different laser powers exhibit an unusual time-dependence. The analysis points towards dynamics taking place on three time-scales. Immediately after laser-excitation a localization of excitons takes place within the femtosecond time-regime. This is followed by exciton-exciton annihilation which is responsible for a fast decay of the exciton population. At later times, excitations being localized on units which are not directly connected remain so that diffusion dominates the dynamics and leads to a slower decay. We thus provide evidence for EEA tracked by time-resolved spectroscopy which has not been reported that clearly before.
Description
Identification of effective exciton–exciton annihilation in squaraine–squaraine copolymers - Physical Chemistry Chemical Physics (RSC Publishing)
%0 Journal Article
%1 C6CP01780K
%A Hader, Kilian
%A May, Volkhard
%A Lambert, Christoph
%A Engel, Volker
%D 2016
%I The Royal Society of Chemistry
%J Phys. Chem. Chem. Phys.
%K ak-engel
%N 19
%P 13368-13374
%R 10.1039/C6CP01780K
%T Identification of effective exciton-exciton annihilation in squaraine-squaraine copolymers
%U http://dx.doi.org/10.1039/C6CP01780K
%V 18
%X Ultrafast time-resolved transient absorption spectroscopy is able to monitor the fate of the excited state population in molecular aggregates or polymers. Due to many competing decay processes, the identification of exciton-exciton annihilation (EEA) is difficult. Here, we use a microscopic model to describe exciton annihilation processes in squaraine-squaraine copolymers. Transient absorption time traces measured at different laser powers exhibit an unusual time-dependence. The analysis points towards dynamics taking place on three time-scales. Immediately after laser-excitation a localization of excitons takes place within the femtosecond time-regime. This is followed by exciton-exciton annihilation which is responsible for a fast decay of the exciton population. At later times, excitations being localized on units which are not directly connected remain so that diffusion dominates the dynamics and leads to a slower decay. We thus provide evidence for EEA tracked by time-resolved spectroscopy which has not been reported that clearly before.
@article{C6CP01780K,
abstract = {Ultrafast time-resolved transient absorption spectroscopy is able to monitor the fate of the excited state population in molecular aggregates or polymers. Due to many competing decay processes{,} the identification of exciton-exciton annihilation (EEA) is difficult. Here{,} we use a microscopic model to describe exciton annihilation processes in squaraine-squaraine copolymers. Transient absorption time traces measured at different laser powers exhibit an unusual time-dependence. The analysis points towards dynamics taking place on three time-scales. Immediately after laser-excitation a localization of excitons takes place within the femtosecond time-regime. This is followed by exciton-exciton annihilation which is responsible for a fast decay of the exciton population. At later times{,} excitations being localized on units which are not directly connected remain so that diffusion dominates the dynamics and leads to a slower decay. We thus provide evidence for EEA tracked by time-resolved spectroscopy which has not been reported that clearly before.},
added-at = {2017-06-20T16:32:41.000+0200},
author = {Hader, Kilian and May, Volkhard and Lambert, Christoph and Engel, Volker},
biburl = {https://www.bibsonomy.org/bibtex/2661ea30977875a10d3e69f04297e0c87/ak-engel-uniwue},
description = {Identification of effective exciton–exciton annihilation in squaraine–squaraine copolymers - Physical Chemistry Chemical Physics (RSC Publishing)},
doi = {10.1039/C6CP01780K},
interhash = {9d72e1349dd4da9153879c94fc0c8f81},
intrahash = {661ea30977875a10d3e69f04297e0c87},
journal = {Phys. Chem. Chem. Phys.},
keywords = {ak-engel},
number = 19,
pages = {13368-13374},
publisher = {The Royal Society of Chemistry},
timestamp = {2017-06-20T16:32:41.000+0200},
title = {Identification of effective exciton-exciton annihilation in squaraine-squaraine copolymers},
url = {http://dx.doi.org/10.1039/C6CP01780K},
volume = 18,
year = 2016
}